Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2/012—Multiple filtering units
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2/011—Instruments for their placement or removal
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2002/016—Filters implantable into blood vessels made from wire-like elements
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0002—Two-dimensional shapes, e.g. cross-sections
  • A61F2230/0028—Shapes in the form of latin or greek characters
  • A61F2230/005—Rosette-shaped, e.g. star-shaped
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0067—Three-dimensional shapes conical
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0093—Umbrella-shaped, e.g. mushroom-shaped

Definitions

• the present invention relates to a medical device apparatus and method for the capturing of thrombus. More particularly, the present invention relates to a retrievable vena cava filter device and a method of retrieving the same from a vessel.
• centering or alignment features have been incorporated into filter designs. Centering has been accomplished by the use of free arms that extend radially outward from the filter to contact the vessel wall at a plane spaced apart from the contact point of the filter legs. While free arm centering designs ensure that the conical filtering section generally remains centered within the vessel, these designs are disadvantageous in that the free arms are prone to vessel perforation, fracture and in some cases misalignment due asymmetrical spacing of the free arms. Moreover, occasionally, when attempting to snare the alignment arras, they will becpme bent upwards making the retrieval of the filter even more difficult.
• filters designed with closed loop structures are difficult to retrieve from the vessel, particularly if a portion of the alignment structure has become incorporated into the vessel wall by endothelial overgrowth.
• Endothelial overgrowth may occur at any point where the filter contacts the vessel wall. Over time, the endothelial overgrowth may partially or completely encapsulate any portion of the filter in contact with the wall. This process is called neointimal hyperplasia and occurs as early as two weeks after implantation.
• the vessel wall responds to a foreign presence such as a filter by increased smooth muscle cell growth and neointimal thickening at the contact points.
• a band of endothelial tissue over a filter segment makes retrieval of the filter from the vessel more difficult, especially those filters designed with a closed loop configuration.
• the filter should be designed to allow percutaneous removal without significant trauma or damage to the vena cava wall even after neointima overgrowth has embedded those portions of the filter that are in contact with the vessel wall.
• a retrievable blood clot filter includes a filter section having a plurality of filter legs, a releasable lock and an alignment section coupled to the filter section.
• the alignment section includes alignment ribs having releasable upstream ends that are locked by the releasable lock.
• the releasable lock is capable of releasing at least one releasable upstream end of the alignment ribs so that during retrieval of the filter, the alignment ribs with their released upstream ends can slide through the endothelial tissue that may have grown around the alignment ribs.
• the releasable lock is capable of releasing the releasable upstream ends of the alignment ribs in response to a force applied to the releasable upstream ends during retrieval of the retrievable blood clot filter.
• the shaft couples the alignment hub to the filter hub even when all of the releasable upstream ends of the alignment ribs are released.
• a blood clot filter including a conical filter section and an alignment section.
• the conical filter section has a filter hub and a plurality of filter legs having downstream ends coupled to the hub and upstream ends that extend radially outwardly.
• the alignment section is spaced from the filter section along a longitudinal axis in a non-overlapping manner.
• the alignment section has an alignment hub and a plurality of alignment ribs having downstream and upstream ends. The alignment ribs extend radially outwardly from the downstream ends and then further extends radially inwardly.
• Figure 1 is plan view of one exemplary embodiment of the vena cava filter device in an expanded state according to the present invention.
• Figure 3 is an illustration of the vena cava filter device in a non-expanded or collapsed state according to the present invention.
• Figure 4 is an exploded perspective view depicting the assembly of the components of the vena cava filter of the present invention.
• Figure 5A is an enlarged partial view of the alignment section and secondary filtering hub prior to attachment according to the present invention.
• Figure 5B is an enlarged partial view of the alignment section and secondary filtering hub after assembly depicting the interlocking relationship between the alignment section and the secondary filtering hub.
• Figure 6A illustrates an enlarged partial plan view of the alignment ribs positioned within and being restrained within the primary filtering hub after final assembly.
• Figure 6B is an enlarged partial cross-sectional view of Figure 6 A taken along lines A-A.
• Figure 7 is a series of cross-sectional partial views of an alignment rib within the filtering hub illustrating the enlarged circled area of Figure 6B.
• Figure 7A is a partial cross-sectional view of an alignment rib within the filtering hub prior to disengagement.
• Figure 7B is a partial cross-sectional view of an alignment rib during the first step of retrieval as force is applied to the upstream segment of the alignment rib.
• Figure 7C is a partial cross-sectional view of an alignment rib as additional force is applied and the alignment rib begins to disengage.
• Figure 7D is a partial cross-sectional view of an alignment rib after it has been released from the receiving pocket of the secondary filtering hub.
• Figure 8 is a side view of the filter device in a deployed state inside a vessel with a snare device attached to the hook of the filter device before retrieval, according to the present invention.
• Figure 9A is a plan view of the filter device with the alignment ribs partially collapsed and partially covered by endothelial tissue overgrowth at the alignment rib contact portion as the retrieval sheath is advanced over the alignment ribs, according to the present invention.
• Figure 9B is an enlarged view of the circled area of Figure 9A.
• Figure 1OA is a plan view of the filter device, illustrating the retrieval sheath being advanced further into the vessel, thereby exerting pressure against the alignment ribs and causing the endothelial overgrowth covering the alignment rib contact portion to cinch inward toward the filter, according to the present invention.
• Figure HA is a plan view of the filter device, illustrating the alignment ribs spontaneously releasing from the filtering section, the alignment rib contact portion spontaneously releasing from the endothelial tissue overgrowth as the retrieval sheath is advanced toward the free ends of the alignment ribs, and the wall-engaging ends releasing from the vessel wall, according to the present invention.
• Figure 12 is a plan view of the partially collapsed filter device inside of the vessel, according to the present invention.
• Figure 13 is a plan view of the filter device in a completely collapsed state inside the retrieval sheath before being removed from the vessel.
• Figure 14 is a plan view of an alternative embodiment of the retrievable filter device of Figure 1.
• upstream and downstream refer to the direction of blood flow within a blood vessel. Accordingly, blood flows from an upstream direction towards a downstream direction. Also, it is important to note that although the filters disclosed herein are capable of being retrieved, they can be used as permanent filters without being retrieved.
• the vena cava filter device 1 is comprised of a conical filtering section 3, an alignment section 5, a center shaft/rod 4 and a retrieval hook subassembly 25.
• the conical filtering section 3 captures and lyses blood clots, anchors the filter device 1, and prevents the filter device 1 from migrating downstream.
• the alignment section 5 has a closed loop geometry
• the center shaft 4 provides a moveable connection between the alignment section 5 and the conical filtering section 3 for retrieval.
• the retrieval hook subassembly 25 allows retrieval of the filter device 1 from the vessel using a snare device or other retrieval device known in the art.
• Each secondary filter leg 29 branches off into two branch legs 27 at a branch point 39 which is upstream of the filter hub 11, Unlike the primary filter legs 13, the upstream ends of the two branch legs of secondary filter legs 29 have a smooth profile without wall- engaging ends and are adapted to simply rest on a vessel wall.
• FIG. 2 a downstream end view of the filter device 1 in an assembled and expanded state is illustrated. Extending radially outward from the retrieval hook subassembly 25 are primary filtering legs 13 and secondary filtering legs 29. Anchoring ends 15 of the primary filtering legs 13 contact and engage the vessel wall, providing an attachment mechanism to prevent filter migration. Secondary filtering legs 29 also contact the vessel wall at a downstream location relative to the primary filtering legs 13.
• the expanded filter 1 diameter will vary depending on the diameter of the patient's vena cava, which will partially constrain the expansion of filter 1 ? but may range from 18 to 23 millimeters for a typical patient.
• the angle of legs 13 proximate to the vessel wall may be reduced when under constraint from the vessel wall, the angle of the legs 13 relative to each other near the center of the vessel remains unchanged, as shown in Figure 2, Specifically, the cross-sectional area between each secondary filter leg 29 from the downstream end 7 to the branch point 39 remains constant even when the relative angle between leg portion 27 and adjacent primary leg 13 has been decreased due to the constraint of the small vessel diameter.
• the filter 1 of the current invention maintains constant area coverage at the center of the vessel. As a result, the filter 1 is less likely to occlude when placed in a small vessel.
• leg branches 27 do not individually connect to the filter hub 11. Rather, a set of two legs 27 merges into a single secondary leg 29, which then connects to the filter hub.
• the secondary filter section provides an increased number of legs extending to the vessel wall for additional filter coverage at the outer circumferential area of the vein while minimizing the amount of filter material at the center of the vessel.
• Prior art filters with increased mass at the center of the filter have been shown to have increased filter occlusion rates.
• the design of this invention overcomes this problem by reducing the number of legs 29 that merge into the hub 11. As shown in Figure 2, the reduced central area profile has only eight legs connecting to the filter at hub 11, with twelve leg ends contacting the vessel wall at an upstream location for enhanced filtering.
• FIG. 3 is a side view of the filter 1 in an assembled, unexpended state.
• the filter 1 is comprised of the hook subassembly 25, a first tubular body 6 which forms the alignment hub 19 and alignment ribs 8, and a second tubular body 17 forming the primary hub 11 and filtering legs 13.
• a third tubular body 18 (not visible in Figure 3) is axially arranged within the second tubular body 17 and forms the secondary hub 35 and filtering legs 29 with their branch leg portions 27.
• Each tubular body 6, 17 and 18 are preferably comprised of material with shape- memory characteristics, such as Nitinol, to allow expansion from a collapsed state illustrated in Figure 3, to a deployed state at body temperature as illustrated in Figure 1.
• Nitinol is an alloy well-suited for vena cava filters because of its shape-memory characteristics, which enables it to return to a pre-determined expanded shape upon release from a collapsed position.
• the tubular bodies 6, 17, and 18 are first cut into the desired configurations using laser-machining techniques commonly known in the art. Other cutting techniques such as photo or acid etching may be used to form the desired cut patterns for the filter device 1.
• the first tubular body 6 which forms the alignment section 5 is approximately 1.1 inches in length.
• the second tubular body 17, from which the primary filtering 3 is cut, is approximately 1.4 inches in length.
• the combined length of tubular body 6 and 17 is approximately 2.5 inches, and the overall length of the device is 2.65 inches, including the assembled retrieval hook subassembly 25, which has an exposed hook portion of approximately 0.15 inches in length.
• the total filter 1 length of 2.65 inches shortens to approximately 2.15 inches after the filter 1 is expanded into the deployed state shown in Figure 1.
• Prior art filters that do provide both centering and conical filtering capabilities generally require larger delivery devices due to the overlap of wire elements when the filter device 1 is in the collapsed state.
• the filter device 1 can be constrained in a delivery device that is substantially equal to the outer diameters of the first and second tubular bodies 6, 17.
• a filter fabricated from a tube with a 0.072 inch outer diameter will be able to be delivered using a sheath with an internal diameter as small as 0.075 inches, or within a 6 French sheath.
• the assembly steps of the filter device 1 are illustrated in Figure 4.
• a center spacer 20 is first inserted into and welded to the secondary filtering hub 35.
• the center spacer 20 is a hollow tubular structure made of Nitinol or other similar material.
• the center spacer 20 lumen is approximately 0.020" with an outer diameter of 0.032" to allow insertion of the spacer 20 into the through lumen of secondary filtering hub 35, which is dimensioned at approximately 0.033".
• Weld hole 37 facilitates welding of the center spacer 20 to the secondary filtering hub 35.
• the center spacer 20 performs the dual function of a spacer and a stopper mechanism.
• the center spacer 20 ensures that the center shaft 4, when inserted through the spacer 20 lumen, is maintained in a centered position within the secondary filtering hub 35 lumen.
• the center shaft 4 has an outer diameter of approximately 0.015" which fits freely within the 0.020" inner diameter of the center spacer 20, allowing the center shaft 4 to move freely in a longitudinal direction relative to the vessel without becoming misaligned and off-center.
• the center spacer 20, in conjunction with stop member 14, also provides a travel stop feature by preventing the upstream end of center shaft 4 from moving completely through the spacer 20 lumen during retrieval.
• the combined secondary filtering hub 35/center spacer 20 subassembly is then inserted into the lumen of primary filtering hub 11 as shown by the dotted line.
• the outer diameter of secondary filtering hub 35 is approximately 0.051" to allow ease of insertion into the primary filtering hub 11 lumen which has a diameter of 0.052".
• the secondary filtering hub 35 with spacer 20 is inserted into the lumen of the primary filtering hub 11, and then welded together using weld hole 43. With this method and configuration, the filtering section 3 maintains an outer diameter in an unexpended state of 0.072".
• the center shaft 4 is then attached to the hook subassembly 25.
• the hook subassembly 25 includes a hook insert section 49 formed of a solid cylindrical element extending in an upstream direction from the base section 45.
• a longitudinally arranged channel 48 is formed in the hook insert section 49.
• the center shaft 4 is inserted into channel 48 and welded in place.
• center shaft 4 is passed through the alignment hub 19 lumen until the upstream edge of alignment hub 19 abuts against outer rim 75 of retrieval hook subassembly 25.
• Pin hole 57 of the alignment hub 19 and pin hole 47 of the hook subassembly 25 are brought into alignment with each other.
• a pin 41 is inserted through the aligned holes to secure the retrieval hook subassembly 25 and the alignment hub 19.
• the pin 41 is dimensioned so as to create an interference fit with the pin holes 57 and 47.
• the pin 41 may be made of any suitable material.
• the pin 41 is at least partially made of Titanium, as illustrated in the preferred embodiment of the present invention.
• Pin 41 is of a length greater than the outer diameter of the alignment hub 19. For example, for a 0.072 inch alignment hub 19 diameter, the pin 41 may be 0.079 inches in length.
• the connected retrieval hook subassembly 25 and the alignment hub 19 are placed in a swaging die and cold swaged to cause the outer surface of the pin 41 to be flush with the outer surface alignment hub 19.
• the swaging process also creates an interference fit between the pin 41 and the aligned pin holes 47 and 57, resulting in a strong, reliable attachment that does not require additional heating of the metal or welding, both of which may compromise the material of which the retrieval hook subassembly 25 and alignment hub 19 are composed.
• the assembled filtering section 3 is then assembled to the alignment section 5 by inserting the downstream end of center shaft 4 through the lumen of center spacer 20 which was previously attached to the secondary filtering hub 35.
• Center shaft stop 14 is then welded to the downstream end of center shaft 4.
• the center shaft stop 14 prevents the filtering section 3 from becoming separated from the rest of the filter device 1 and ensures alignment of the filtering section 3 during retrieval.
• the center shaft 4 is stopped from additional downstream travel when the center shaft stop 14 comes into contact with the downstream end of the center spacer 20.
• the rod stop 14, which has a diameter of approximately 0.032" is too large to fit through the 0.020" of the spacer 20, and accordingly, is stopped from further downstream movement.
• the shaft 4 disclosed herein with reference to Figure 4 is a rigid rod
• the shaft 4 may be comprised of a non-rigid material formed as a cable, wire or polymer connecting element. With this design, the connecting element 4 does not need to extend upstream of the primary filter hub 11.
• the last assembly step is to insert the free upstream ends 23 of alignment ribs 8 into an interlocking relation with a releasable lock in the secondary filter hub 35. This last step is illustrated more clearly in Figure 5A - 5B and 6A - 6C.
• Figure 5A and Figure 5B depict partial further enlarged views of the interlocking relationship between the alignment ribs 8 and the secondary filtering hub 35.
• each alignment rib 8 of alignment section 5 is laser cut in a pattern forming an engaging tab 24.
• Each engaging tab 24 formed at the upstream end 23 of the alignment rib 8 includes a pocket engaging surface (projecting surface) 88, barb extensions 90, inwardly tapered sections 92 and a downstream face 94.
• the engaging tab 24 profile includes the two pocket engaging surfaces 88 that extend outwardly from the upstream end 23, and barb extensions 90.
• Barb extensions 90 form an expanded width of approximately 0.022 inches relative to the width of upstream ends 23, which are 0.016 inches.
• Engaging tab 24 also include two inwardly tapered sections 92 which terminate in downstream engaging face 94.
• Receiving pocket 22 of hub 35 is dimensioned to receive engaging tab 24 in an interlocking relationship, as shown in Figure 5B.
• Alignment rib receiving portion 98 is dimensioned at 0.018 inches to allow upstream end 23 of rib 8, which is 0.016 inches, to be positioned within pocket 22 snugly, but without interference.
• barb receiving section 100 is dimensioned at 0.026 inches in width to freely accommodate pocket engaging surfaces 88 and barb extensions 90, while simultaneously preventing disengagement of tab 24 when the alignment rib 8 is under axial force.
• Taper portion 102 of the receiving pocket 22 is dimensioned to be approximately 0.001 inch larger than the corresponding tapered section 92 of engaging tab 24 to allow a small clearance between the components without allowing movement.
• the releasable alignment ribs 8 are restrained from movement in an inwardly radial direction by the center spacer 20 and restrained from movement in an outwardly radial direction by the inner wall of the segment 16. As previously discussed, the alignment rib 8 is also prevented from movement in an axial direction by the profile of the receiving pocket 24, which prevents movement of the barb extension 90. .
• an implantable, retrievable filter 1 that will not release from a closed loop to an open loop structure under normal body movements experienced during implantation due to the interlocking design.
• the device 1 provides for central alignment within the vessel using a closed loop configuration that will not perforate the vessel wall, become entangled or fracture.
• the present invention also pertains to a method of retrieving the implanted filter device 1 of the present invention from a vessel of a patient body.
• This method utilizes the alignment ribs' releasing feature to facilitate removal under those conditions in which filter portions have been encapsulated in endothelial overgrowth.
• the method involves inserting a retrieval sheath into the vessel, capturing the filter retrieval hook subassembly with a snare, advancing the retrieval sheath over the alignment ribs, thereby applying a prying force to release the alignment ribs from the filtering hub, and sliding the free rib ends through the overgrowth and into the sheath.
• the method further involves the steps of further advancing the retrieval sheath over the filtering section thereby capturing the filter legs within the sheath and removing the retrieval sheath and filter 1 from the vessel.
• Figures 8 through 13 The retrieval steps of this method are illustrated in Figures 8 through 13 and also with reference to Figure 7A-7D.
• Figures 7A - 7D represent the circled area of Figure 6B and illustrate the sequence of steps by which the engaging tab 24 is released by retrieval forces during removal of the filter 1 through endothelial tissue.
• Figure 8 depicts a side view of the filter device 1 in an expanded state inside of a vessel 61 at the beginning of the filter device 1 retrieval process.
• the filter device 1 In the deployed state the filter device 1 is in an expanded position in the vessel 61, as shown in Figure 8.
• the alignment ribs 8 extend radially outward from alignment hub 19 to contact the vessel wall at alignment rib contact portions 10, before extending inwardly to the filtering hub 11 in a closed loop configuration.
• the alignment rib contact portions 10 of the alignment ribs 8 are shown encapsulated in the endothelial overgrowth band 73 of the vessel wall 65.
• the filter legs 13 extend radially outward from the primary filtering hub 11 to contact the vessel wall 65 at wall engaging ends 15.
• the secondary filtering legs 29 also extend radially outward from the filtering hub 11 to contact the vessel wall 65 at a separate plane from wall engaging ends 15.
• a sheath 78 coaxially surrounding a snare device 63 is inserted into the vessel 61 and advanced to the filter 1.
• the snare device 63 is then advanced beyond the distal end 79 of the sheath 78, as shown in Figure 8.
• the hook 51 of the retrieval hook subassembly 25 is captured by looping the snare wire 64 of the snare device 63 around the hook 51 and applying tension to securely engage the hook 51 , as is well known in the art.
• the filtering hub 11 including the spacer 20 is slidably and coaxially mounted onto the center shaft 4.
• the center shaft 4 thus functions to maintain axial alignment of both the alignment section 5 and the filtering section 3 during retrieval.
• the center shaft 4 also provides a central travel rail over which the alignment ribs 8 can elongate longitudinally without causing the filtering hub 11 to move.
• the band of endothelial overgrowth 73 at the wall contacting portion 10 of the ribs 8 is illustrated in the enlarged view of Figure 9B.
• the portion of the vessel 61 associated with the encapsulated alignment rib wall contacting portion 10 will be drawn inwardly toward the center of the vessel 61 as the alignment rib 8 begins to collapse.
• the band of endothelial overgrowth 73 is pulled inwardly and slides in an upstream direction along the alignment rib 8 toward the filtering hub 11.
• the tapered forward segment 16 of hub 11 may undergo a small amount of material deformation as pressure is applied by the engaging tab 24 against segment 16, causing it to flex slightly as tab 24 disengages from receiving pocket 22.
• the flexing of the hub forward segment 16 is illustrated in Figures 7B and 7C.
• segment 16 of primary filtering hub 11 will undergo deformation within the elastic limit, thus returning to its original shape after the alignment ribs 8 are released from the hub 11.
• the hub 11 may be made of material that will exceed the elastic limit when force is applied by the engaging tab 24, resulting in the segment 16 of hub 11 remaining in a slightly flexed position.
• Figure 1 IA and 1 IB depict the filter device 1 after the alignment ribs 8 have been completely released from the filtering hub 11, but prior to retraction of the rib 8 through the endothelial band 73.
• the radially outward force created by the endothelial band 73 along with the force created by the retraction of the snare 63 within the sheath 78 cause the engaging tab 24 to completely disengage from the receiving pocket 22.
• the vessel wall 65 remains partially collapsed by the alignment ribs upstream ends 23, which are disengaged from the filter 1, but remain encapsulated within the vessel wall 65. Except for the upstream ends 23, the alignment ribs 8 are completely collapsed, elongated against the center shaft 4 and constrained within the sheath 78.
• the snare wire 64 is further retracted. This movement causes the upstream ends 23 of the alignment ribs 8 be pulled through the endothelial overgrowth 73 in a downstream direction exiting through exit point 104. The upstream ends 23 of the ribs 8 are pulled through the overgrowth 73 at an angle that leaves only an opening 104, thus minimizing vessel trauma, and avoiding longitudinal tearing through the endothelial tissue 73.
• a method of filter retrieval is provided that is minimally traumatic to the vessel wall and does not cut through or otherwise damage the vessel 61.
• the vessel wall 65 is no longer constrained by the filter 1 and the vessel 61 returns to its original shape, as shown in Figure 12.
• the retrieval sheath 78 As the retrieval sheath 78 is advanced, it completely encloses the alignment section 5 and the primary filtering hub 11. The primary filtering legs 13 and the secondary filtering legs 29 remain deployed, but begin to disengage from the vessel wall 65.
• the sheath 78 is then further advanced over and completely encloses the plurality of primary filtering legs 13 and the secondary filtering legs 29.
• the filter device 1 becomes completely enclosed within the retrieval sheath 78.
• the entire collapsed filter device 1, along with the sheath 78 is then removed as a single unit from the blood vessel 61.
• the method may also be used to retrieve a filter that had not been incorporated into the vessel wall 65. If there is no or minimal endothelial overgrowth 73, the radially outward prying force created by the band of endothelial tissue 73 as it slides upstream along the alignment rib 8 is not created. In the absence of this force, the alignment ribs 8 will collapse inwardly against the center shaft 4 but will not release from the filtering hub 11. Instead, the filter collapses in a linear fashion as previously described, with the alignment ribs 8 remaining captured within the filtering hub 11.
• the method may also be effectively used to retrieve a vena cava filter 1 that has one or more but not all alignment ribs 8 encapsulated within endothelial bands 73 of tissue.
• those alignment ribs 8 that are encapsulated will release during retrieval due to the radially outward force created by the bands 73 as they slide upstream toward the filtering hub 11.
• those alignment ribs 8 that have not been incorporated into the vessel wall 65 will flatten out against the center shaft 4 but will not undergo sufficient radially outward force to release from the filtering hub 11.
• a retrievable filter 1 is provided that can be successfully retrieved in the absence or presence of vessel overgrowth on one or more alignment ribs 8.
• the retrievable filter device 80 includes a filter section 3 and an alignment section 5, except that the upstream ends of the alignment ribs 8 are fixedly attached to the filter hub 11.
• the alignment section 5 and filter section 3 are optimally comprised of a single tubular structure.
• Some of the filter legs 13 may include vessel wall-engaging ends 15 at their upstream ends while some may have a smooth profile without such wall-engaging ends at their upstream ends.
• the filter section 3 and alignment section 5 are longitudinally spaced from one another in a non-overlapping relationship. This embodiment may be placed as a permanent implant or as short term retrieval device which is removed prior to significant overgrowth of vessel tissue, typically four to eight weeks.
• the downstream end of the filter hub 11 may be sharpened to incise any tissue that may be present during retrieval.
• Figure 14 shows the filter legs 13 without any branches
• the filter 80 can be provided with the primary filter legs 13 and secondary filter legs 29 each with two branch legs 27 as shown in Figure 1.
• the closed loop configuration of device depicted in Figure 14 is advantageous over prior art filters with centering structures comprised of individual legs with free ends that are prone to entanglement and misalignment.
• the device is formed from a single Nitinol or other metallic tube with no welded joints. This construction is cost-effective and provides enhanced structural integrity and strength over welded devices.
• the single tube construction with the longitudinal separation of the alignment and conical filtering sections allows the device to be constrained within a smaller delivery system that is substantially equal to the outer diameter of the tube.
• Figures 15A and 15B show alternative structures of a releasable lock and releasable upstream ends of the alignment ribs.
• the releasable lock may be designed to automatically release or weaken the coupling after a predetermined time has elapsed.
• the tapered forward segment (cover piece) 16 of the primary filtering hub 11 as shown in Figures 6A and 6B which circumferentially surrounds and covers the engaging tabs 24 may be comprised of a biodegradable material such as polyglycolide, polylactide, or other synthetic polymer commonly known in the art.
• the material is designed to gradually degrade and be absorbed by the body over a period of time, typically two weeks to six months, depending on the material formulation. During this period of time, the vessel wall contact points 10 of the filter will become incorporated into the vessel wall, thus stabilizing the filter within the vessel. Once the biodegradable material has been absorbed by the body, the engaging tabs 24 are no longer restrained and will disengage from hub 11 with relatively little force. The endothelial overgrowth at the vessel wall contact points of the filter immobilizes the alignment ribs preventing misalignment and migration of the device as well as perforation of the vessel by the ribs.
• the releasable upstream ends 23 of the alignment ribs 8 can be permanently attached to the hub U and be made of biodegradable material at point 84 as shown in Figure 15B. After a predetermined time period, the releasable upstream ends 23 of the ribs 8 will be released into open ends or will be sufficiently weakened so that the upstream ends 23 of the alignment ribs 8 will break with relatively little force. In this case, the filter hub 11 acts as the releasable lock.
• the releasable lock may be designed with releasable upstream ends 23 that are structurally weakened relative to the remaining portions of the alignment ribs 8 to deform or break under a predetermined retrieval force.
• the alignment ribs 8 may include releasable upstream ends 23 that have a reduced profile section as shown at 84 in Figure 15B (either in width, thickness or both), which will deform or break at a lower retrieval force than the other filter components, thereby causing the alignment rib upstream ends 23 to be released from hub 11.
• the reduced profile of the upstream ends 23 can be a reduced thickness or width of the tabs 24 such that they will deform or break at a lower retrieval force than the other filter components.
• the alignment ribs 8 may include releasable upstream ends 23 that have a reduced profile section at point 84 as in Figure 15B and be made of biodegradable material at the same point 84.
• each engaging tab 24 and recess 22 may be laser cut so as to create an interference friction fit as shown in Figure 15 A.
• the engaging tabs which have a slightly larger profile than the receiving recesses 22, are forcibly inserted into the recesses.
• the material interference between each engaging tab 24 and recess 22 creates a friction fit which will release only under a retrieval force sufficient to overcome the retaining force.
• the advantage of this embodiment is that it does not rely on the endothelial overgrowth band to create a prying force. Instead the friction fit may be overcome by a direct longitudinal force.
• vena cava filter 1 Other configurations and methods of retrieving a vena cava filter 1 are also possible. Modifications of the details illustrated in this disclosure, including filter and component shapes, numbers, wall-engaging designs, dimensions, materials, methods of construction, and methods of use, are within the scope of this invention. For example, the number of filtering legs on both the primary and secondary filtering structures may be varied. The filter 1 may be assembled without utilizing a secondary filtering structure 26. The assembly methods, component dimensions and materials may be varied. In addition, the interlocking profiles of the alignment ribs 8 and filtering hub 11 may also be modified and remains within the scope of the present invention.
• Any engaging tab 24 and receiving pocket 22 profile may be used if it is configured to provide a holding force in an axial direction and allow release when an outwardly radial force is present.
• Tab shapes including circular, semi-circular, rectangular, teardrop or elliptical are within the scope of the invention.
• the center shaft 4 component may be of a variable length in a spring configuration or comprised of a non-metallic material such as a nylon wire.
• the center shaft 4 may be of any configuration that provides a travel path that exceeds the elongated length of the alignment section. Accordingly, the scope of the invention is not limited to the foregoing specification.

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• 2007
  • 2007-01-22 EP EP07710259A patent/EP1973597A2/de not_active Withdrawn
  • 2007-01-22 US US11/625,723 patent/US8475488B2/en not_active Expired - Fee Related
  • 2007-01-22 CA CA002631295A patent/CA2631295A1/en not_active Abandoned
  • 2007-01-22 JP JP2008551575A patent/JP2009523582A/ja active Pending
  • 2007-01-22 WO PCT/US2007/060866 patent/WO2007085025A2/en active Application Filing
  • 2007-01-22 AU AU2007205867A patent/AU2007205867A1/en not_active Abandoned
• 2009
  • 2009-07-23 US US12/508,175 patent/US9055996B2/en not_active Expired - Fee Related

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